Thermostatically operated safety device



Sept. 3, 1957 s. G. ESKIN THERMOSTATICALLY OPERATED SAFETY DEVICE Filed Jan. 51, 1956 fiYZ EZWZUF SAMUEL G E sznv dw yw flzz THERMGSTATICALLY OPERATED SAFETY DEVICE Samuel G. Eskin, Chicago, Ill., assignor to The Dole Valve Company, Chicago, 111., a corporation of Illinois Application January 31, 1956, Serial No. 562,415

Claims. (Ci. 200-140) This invention relates to improvements in thermostatically operated safety devices and more particularly relates to such devices adapted to act as safety devices for gas burners and the like.

A principal object of the invention is to provide a simple and positively acting thermostatic device adapted to complete an electric circuit upon a predetermined rise in temperature sensed by the thermostatic element of the device.

Still another object of my invention is to provide a simpler form of thermostatically operated device than formerly in which a diaphragm is extended from a diaphragm plate by the expansion of mercury in a capillary tube upon predetermined rises in temperature, and in which a snap acting switch is moved into position to complete an electric circuit upon expansion of the diaphragm from the diaphragm plate and is so arranged as to accommodate .overtravel of the diaphragm without damage to the switch.

Still another object of the invention is to provide a simple form of thermostatic device and snap acting switch actuated thereby, which may readily be incorporated in the valve body of a gas valve and the like, to control operation thereof, and which is arranged with a view toward simplicity in structure and operation, low cost, long life and ready assembly in and disassembly from the gas valve.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

Figure 1 is a sectional view taken through the end of a valve body having a thermostatically operated safety device constructed in accordance with the invention, incorporated as a part of a valve;

Figure 2 is a sectional view taken substantially along line IIII of Figure 1; and

Figure 3 is a diagrammatic view showing the bulb of the thermostat in association with a pilot burner.

In the drawing, I have shown a valve body of a gas valve, such as may contain a master gas supply valve (not shown) and a main burner valve (not shown), controlling the flow of gas to a pilot burner 11 and to a main burner 12. The valve body 10 is shown in the drawing as having an open top closed by a cover 13 and an open end closed by a plate 15 having a shallow metal diaphragm 16 secured thereto at its periphery on the inside thereof and extending over a passageway 17 extending through said plate to said diaphragm in alignment with the center thereof. A fitting 19 having a central passageway 20 leading therethrough is welded or otherwise secured to the outside of the plate 15, with the passageway 20 in communication with the passageway 17 leading through the plate 15. A capillary tube 21 has communication with the passageway 20 in the fitting 19 and extends therefrom. The capillary tube 21 may be suitably secured to the fitting 19 in leakproof relation with respect thereto and has a closed outer States Patent 0 2,805,303 Fatented Sept. 3, 1957 1;. end portion 22, which may be in the form of a bulb positioned adjacent the pilot burner 11 close to the flame thereof. The capillary tube 21 may be filled with mercury and may be made from a stainless steel which is unaffected by the corrosive action of the gas flame.

The diaphragm 16, on the opposite side of the plate 15 from the fitting 19 and capillary tube 21, is shown as having an annular rim 23 abutting the plate 11 and secured and sealed thereto as by seam-welding. The inner margin of the annular rim 23 terminates in an outwardly flared or dished portion 24 having an inwardly dished or concave central portion 25 having an operating button 26 mounted in the center thereof and extending therefrom within the valve casing 10. The inwardly dished portion 25 of the diaphragm 16 engages the inner face of the plate 15 by the resiliency of the diaphragm, and is extended from said plate upon expansion of the mercury within the capillary tube 21 as the closed end 22 thereof is subjected to the heat of the flame issuing from the pilot burner 11, and returns into engagement with the plate 15 to the position shown in Figure 1 by its own resiliency upon reductions in temperature and contraction of the mercury within the capillary tube 21.

Within the casing 10 and carried in opposite side walls 27 thereof is a transverse shaft 29 forming a pivot shaft for a switch arm 30. The shaft 29 is shown on the drawing as extending transversely of the diaphragm 16 above the center thereof and as being spaced inwardly of said diaphragm along the walls 27 of the valve casing.

The switch arm 30 is shown as being in the form of a relatively flat plate having parallel inturned side walls 31 extending inwardly in parallel relation with respect to each other, and pivotally mounted on the transverse shaft 29 and positioning said switch arm in spaced relation with respect to the shaft 29 toward the diaphragm 16. A collar 32 encircles one end of the shaft 29 and is interposed between the inside of a side wall 27 and the outside of an inturned wall 31 of the switch arm 30 to space said switch arm from said wall. A torsion spring 33 encircles the opposite end of the shaft 29 from the collar 32 and has one arm 35 extending along the inturned wall 31 and having engagement therewith adjacent the lower end thereof and has another arm 36 hooked within the wall 27, to bias the switch arm 30 toward the diaphragm 16.

A means is provided on the switch arm 30 beneath the pivot shaft 29 therefor to engage the button 26 on the diaphragm 16 and effect operation of the switch arm 30 against the bias of the spring 33, which is herein shown as comprising a machine screw 37 threaded within a collar 39 which may be snapped or otherwise secured to an apertured portion 40 of the switch arm 30.

The switch arm 30 has an open portion 43 leading therethrough adjacent the lower end thereof, through which extends a plunger 44 of a switch 45 engageable with an abutment member 47 extending inwardly from the plate 15 at the lower end of the diaphragm 16. The switch 45 is suitably connected to the switch arm 30 and may be a well known form of 2-way snap acting switch completing a circuit through conductors 48 and 46 when the plunger 44 is depressed by engagement with the abutment member 47 and completing a circuit through conductors 48 and 49, when the plunger 44 is extended by disengagement of said plunger from the abutment member 47.

While I have shown three conductors 48, 46 and 49 leading from the snap acting switch 45 and have described the switch as completing a circuit through the conductors 48 and 46 when the plunger 44 is depressed, and as com pleting a circuit through the conductors 48 and 49 when the plunger 44 is extended, it should be understood that the snap acting switch 45 may be a single acting switch in which a circuit may be completed as the plunger 44 is extended by disengagement from the abutment member 47, and a circuit may be broken by engagement of the plunger 44 with the abutment member 47, and vice versa.

The particular thermostatically operated electric switch shown and described is particularly suitable for use as a flame safety switch in the control circuit for a gas burner in which a circuit is completed when the plunger 44 is depressed by engagement with abutment 47 by the spring 36 to initially energize an igniter (not shown) for the pilot burner 11, and in which the circuit is broken and a second circuit is completed as the heat of the pilot flame expands the mercury in the capillary tube 21 to extend the diaphragm 16 from the plate 15 and pivot the switch arm 3% in a counterclockwise direction to disengage the plunger 44 from the abutment 47. The heat of the pilot flame maintaining the tip of the capillary tube bot, will supply the necessary pressure to hold the diaphragm 16 and switch arm 30 in their extended positions to maintain a circuit to hold the main burner Valve open until the circuit is deenergized by turning off the supply of electricity to the burner circuit, the failure of the electric circuit, or the failure of the pilot flame, in which case the tip 22 of the capillary 21 will cool and the switch arm 39 will be returned to the position shown in Figure l by the torsion spring 33, deenergizing the circuit to the main burner valve and completing an igniter circuit. The igniter and main burner circuits are well known to those skilled in the art so need not herein be shown or described in detail.

It may be seen from the foregoing that a simple compact and positively acting thermostatically operated snap acting switch has been provided which may readily be assembled to and incorporated as a part of a gas valve for controlling the energizing circuits to the solenoidoperated valves thereof.

It may be further seen that the switch arm 3% is freely pivotally movable outwardly of the diaphragm 16 against the bias of the torsion spring 33 upon extensible movement of the diaphragm 16 with respect to the plate 15, and that said switch arm and the switch carried thereby are so arranged as to accommodate unlimited extension of the diaphragm it: with respect to the plate 11 without damage to the switch or switch arm, thus making it unnecessary to provide the usual safety means preventing overtravel of the thermostatic element and the mechanism operated thereby.

It will be understood that various modifications and variations of the present invention may be effected without departing from the spirit and scope of the novel concepts thereof.

I claim as my invention:

1. in a thermostatically operated switch, a plate having a fiat metal diaphragm sealed to said plate adjacent its margin for extensible movement with respect thereto, an inlet through said plate to said diaphragm, a capillary tube leading from said inlet and containing an expansible fluid at its outer end, a switch arm pivoted in spaced relation with respect to said diaphragm and extending thereover, an engaging connection between switch arm and diaphragm for pivotaily moving said switch arm upon extensible movement of said diaphragm with respect to said plate, means biasing said engaging connection toward said diaphragm, and switching means carried on said switch arm and operable to complete one electric circuit upon movement of said switch arm away from said plate effected by extensible movement of said diaphragm with respect to said plate and to complete a second circuit upon retractible movement of said diaphragm with respect to said plate and pivotal movement of said switch arm toward said plate.

2. In a thermostatically operated electric switching device, a flat plate having a shallow metal diaphragm on one side thereof having a fiat annular rim engaging and sealed to said plate and also havin a portion spaced inwardly of said rim extending outwardly from said rim and dished inwardly to engage said plate, said plate having a passageway leading therethrough to said diaphragm and having a capillary tube containing an expansible fluid leading therefrom and closed at its outer end for association with a source of heat, a switch arm pivoted in spaced relation with respect to said diaphragm, engaging means intermediate the ends of said switch arm having engagement with said diaphragm, a spring biasing said engaging means into engagement with said diaphragm, a stationary abutment on said plate, and a twoway snap acting switch on said switch arm on the side thereof opposite said plate and having a depressible plunger extending through said switch arm for engagement with said abutment member, said switch being oper ated to complete one electric circuit upon extensible movement of said diaphragm with respect to said plate and disengagement of said plunger from said abutment member and thereby accommodating overtravel of said diaphragm and switch arm without damaging said switch and to complete a second electric circuit upon movement of said switch arm toward said plate efiected by retractible movement of said diaphragm.

3. In a thermostatically operated electric switching means, a fiat plate having a shallow metal diaphragm on one side thereof having a flat annular rim engaging and sealed to said plate and also having a portion spaced inwardly of said rim dished to engage said plate, said plate having a passageway leading therethrough to said diaphragm and having a capillary tube leading from said passageway and containing mercury and closed at its end for association with a source of heat, a switch arm pivoted in spaced relation with respect to said diaphragm, a member threaded in said switch arm intermediate the ends thereof having adjustable engagement with said diaphragm, to pivot said switch arm outwardly of said diaphragm upon extensible movement of said diaphragm with respect to said plate, an abutment on said plate facing said switch arm, a two-way snap acting switch mounted on the opposite side of said switch arm from said plate and having an operating plunger extending therethrough for engagement with said abutment and movable out of engagement with said abutment to complete an electric circuit, and spring means biasing said switch arm and threaded member into engagement with said diaphragm and biasing said plunger into engagement with said abutment to complete one electric circuit and accommodating movement of said switch arm and switch away from said abutment to release said plunger to complete a second electric circuit upon extensible movement of said diaphragm with respect to said plate.

4.- In a thermostatically operated electric switching means and in combination with a valve casing, a plate closing an end of said casing, a shallow metal diaphragm on the inside of said plate'within said casing and having a flat annular rim engaging and sealed to said plate and also having a portion spaced inwardly of said rim extending outwardly of said plate and dished in to engage said plate adjacent its center, said plate having a passageway leading therethrough to the outside thereof and having a capillary tube containing mercury and sealed at its end leading therefrom, a transverse shaft pivoted within said casing and spaced inwardly of said diaphragm and extending thereacross, a switch arm pivotally mounted on said shaft and extending therefrom along and beyond said diaphragm, an engaging member on said switch arm engageable with said diaphragm adjacent the center thereof, an abutment member on said plate extending inwardly of said casing, a snap acting switch carried by said switch arm on the opposite side thereof from said abutment member and having a depressible plunger engageable withsaid abutment member, and spring means biasing said engaging member into engagement with said diaphragm and biasing said plunger into engagement with said abutment member to depress the same, said switch completing a circuit upon movement of said switch arm and plunger away from said plate effected by extensible movement of said diaphragm with respect to said plate and thereby accommodating overtravel of said diaphragm and switch arm without injury to said switch.

5. In a thermostatically operated electric switching means and in combination with a valve casing, a plate closing an end of said casing, a shallow metal diaphragm on the inside of said plate having a flat annular rim engaging and sealed to said plate and having a portion spaced outwardly of said plate and a central portion dished inwardly to engage said plate, said plate having a passageway leading therethrough to said diaphragm and having a capillary tube filled with mercury and closed at its outer end leading therefrom, a shaft pivoted to said valve casing at its ends and extending over said diaphragm, a switch arm pivotally mounted on said shaft and extending along said diaphragm beyond the end thereof, a threaded engaging member adjustably threaded in said switch arm for engagement with said diaphragm adjacent the center thereof, an abutment member on said plate extending inwardly of said casing, a snap acting switch on the opposite side of said switch arm from said plate and having a depressibie plunger extending through said switch arm for engagement with said abutment member, and a torsion spring coiled about said shaft and having one end secured to said casing and an opposite end engaging said switch arm for biasing said plunger into engagement with said abutment member and accommodating movement of said switch arm in a direction to disengage said plunger from said abutment member and effect the completion of an electric circuit, said switch arm and switch moving away from said abutment member to complete an electric circuit and thereby accommodating overtravel of said diaphragm and switch arm without injuring said switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,562,385 Marcellus Jan. 31, 1951 2,637,794 Grotenhouse May 5, 1953 2,688,064 Traver Aug. 31, 1954 2,748,225 Kautz May 29, 1956 

